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Chapter 9 Electronic Structure and Periodic Trends

9.3

Energy Levels, Sublevels, and Orbitals

Copyright © 2008 by Pearson Education, Inc.Publishing as Benjamin Cummings

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Energy Levels

Energy levels • Are assigned quantum numbers n = 1, 2, 3, 4 and

so on.• Increase in energy as the value of n increases.• Have a maximum number of electrons equal to

2n2.

Energy level Maximum number of electrons

n = 1 2(1)2 = 2(1) = 2

n = 2 2(2)2 = 2(4) = 8

n = 3 2(3)2 = 2(9) = 18

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Sublevels• Contain electrons with the same energy.• Are found within each energy level. • Are designated by the letters s, p, d, f.

The number of sublevels is equal to the value of the principal quantum number (n).

Sublevels

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Number of Sublevels

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Electron Capacity

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Table 9.6

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Energy of Sublevels

In any energy level, • The s sublevel has the lowest energy. • The s sublevel is followed by the p, d, and f

sublevels in order of increasing energy.• Higher sublevels are possible, but only s, p, d,

and f sublevels are needed to hold the electrons in the atoms known today.

Do Now

How many total electrons are in Li, C, Mg, Xe?

What energy level is the last electron in for Be, Cl, B?

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Orbitals

An orbital • Is a three-dimensional space

around a nucleus where an electron is found most of the time.

• Has a shape that represents electron density (not a path the electron follows).

• Can hold up to 2 electrons.• Contains two electrons that must

spin in opposite directions.

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s Orbitals

An s orbital • Has a spherical shape

around the nucleus.• Increases in size around

the nucleus as the energy level n value increases.

• Is a single orbital found in each s sublevel.

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p Orbitals

A p orbital • Has a two-lobed shape .• Is one of three p orbitals that make up each p

sublevel.• Increases in size as the value of n increases.

Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

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Sublevels and Orbitals

Each sublevel consists of a specific numberof orbitals. • An s sublevel contains one s orbital.• A p sublevel contains three p orbitals.• A d sublevel contains five d orbitals.• An f sublevel contains seven f orbitals.

Copyright © 2008 by Pearson Education, Inc.Publishing as Benjamin Cummings

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Indicate the number and type of orbitals in eachof the following:

A. 4s sublevel

B. 3d sublevel

C. n = 3

Learning Check

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Indicate the number and type of orbitals in each ofthe following:

A. 4s sublevel one 4s orbital

B. 3d sublevel five 3d orbitals

C. n = 3 one 3s orbital, three 3p orbitals,

and five 3d orbitals

Solution

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The number of

A. electrons that can occupy a p orbital is

1) 1 2) 2 3) 3

B. p orbitals in the 2p sublevel is

1) 1 2) 2 3) 3

C. d orbitals in the n = 4 energy level is

1) 1 2) 3 3) 5

D. Electrons that can occupy the 4f sublevel are

1) 2 2) 6 3) 14

Learning Check

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The number of

A. electrons that can occupy a p orbital is

2) 2

B. p orbitals in the 2p sublevel is

3) 3

C. d orbitals in the n = 4 energy level is

3) 5

D. Electrons that can occupy the 4f sublevel are

3) 14

Solution